KR20210109554A - Resin composition for powder coating - Google Patents

Abstract

The present invention relates to a resin composition comprising a blend of, based on the total weight of a fluoropolymer resin and a semi-crystalline polymer resin:
a) from 10 to 90% by weight of at least one fluoropolymer resin and
b) from 90 to 10% by weight of at least one semi-crystalline polyester resin.
The present invention also relates to a process for preparing such a resin composition, to a powder coating composition comprising such a resin composition, and to the use of such a resin composition, in particular for powder coatings for construction.

Description

Resin composition for powder coating

The present invention relates to novel resin compositions based on fluoropolymer and semi-crystalline polyester resins useful for powder coating, and to methods for preparing such compositions.

As concerns about environmental pollution grow, the coatings industry is moving towards being free of volatile organic compounds (VOCs).

Powder coating is an environmentally promising technology because it contains no VOCs and does not require exhaust treatment or wastewater treatment. Also, excess material can be recovered.

Powder coatings based on acrylic, polyester and epoxy resins have been used historically, but they exhibit poor weather resistance.

On the other hand, coatings based on fluoropolymers are weather-resistant. However, fluoropolymers are difficult to pulverize into powders, and coating materials comprising fluorinated resins generally contain water or solvents and are not in powder form.

In order to solve the above-mentioned problems, attempts are being made to develop a powder coating containing a fluoropolymer and another resin.

Document EP 3 165 581 discloses a composition for a powder coating material comprising polyvinylidene fluoride and an acrylic resin, and a first powder comprising the composition and a second comprising an acrylic resin, polyester resin, urethane resin, epoxy resin or silicone resin A powder coating material comprising two powders is disclosed.

Document US 2015/0072151 describes a powder coating composition comprising a fluorinated resin and a polyester polymer, the polyester polymer comprising _{units derived from C 8-15} aromatic polybasic carboxylic acid compounds and C _2-10 polyhydric alcohol compounds Includes units derived from

Most of the polyesters available are amorphous polyesters. However, these amorphous polyester resins are not compatible with fluoropolymer resins, which results in inhomogeneous blends when these two resins are mixed. This incompatibility limits the amount of fluoropolymer resin that can be incorporated into the resin blend, resulting in coatings with reduced quality and weatherability.

In addition, it is important that the coating has good resistance to solvents, as it can be cleaned with a variety of chemicals during use.

Therefore, there is a need for a resin composition that can produce a coating having excellent weather resistance and excellent solvent resistance, and can be economically and easily made into powder.

It is a first object of the present invention to provide a resin composition comprising, based on the total weight of a fluoropolymer resin and a semi-crystalline polymer resin, a blend of:

a) 10 to 90% by weight of at least one fluoropolymer resin and

b) 90 to 10% by weight of at least one semi-crystalline polyester resin;

The semi-crystalline polyester resin preferably has a linear aliphatic and/or cycloaliphatic structure.

In some embodiments, the semi-crystalline polyester comprises, preferably consists of, units derived from:

- at least a poly-carboxylic acid selected from linear aliphatic dicarboxylic acids and/or cycloaliphatic dicarboxylic acids, and

- At least a polyol selected from linear aliphatic diols and/or cycloaliphatic diols.

In some embodiments, the poly-carboxylic acid is selected from linear aliphatic C ₄ -C ₈ dicarboxylic acids, preferably linear aliphatic C ₄ -C ₆ dicarboxylic acids, and/or cycloaliphatic dicarboxylic acids, more preferably selected from adipic acid, succinic acid, 1,5-pentanedioic acid, 1,4-cyclohexanedicarboxylic acid, and combinations thereof; The polyol is selected from linear aliphatic C ₂ -C ₈ diols, preferably linear aliphatic C ₂ -C ₆ diols, more preferably linear aliphatic C ₄ -C ₆ diols, and/or cycloaliphatic diols, more preferably 1,6-hexanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, and combinations thereof.

In some embodiments, the melting temperature of the semi-crystalline polyester resin is between 75°C and 150°C, preferably between 90°C and 130°C.

In some embodiments, the glass transition temperature of the semi-crystalline polyester resin is less than 55° C., preferably -20 to 50° C., more preferably -15 to 40° C. as measured by DSC at a heating rate of 10° C./min. am.

In some embodiments, the semi-crystalline polyester resin has a hydroxyl number of 15 to 70 mg KOH/g, preferably 20 to 40 mg KOH/g and less than 10 mg KOH/g, preferably less than 5 mg KOH/g. has an acid value of

In some embodiments, the number average molecular weight Mn of the semi-crystalline polyester is from 1500 to 15000, preferably from 2000 to 5000.

In some embodiments, the semi-crystalline polyester resin has a heat of fusion of 20 to 100 J/g, preferably 25 to 90 J/g, as measured by DSC at a heating rate of 10° C./min.

In some embodiments, the semi-crystalline polyester resin has a melt viscosity of 0.005 to 10 Pa· ^{s at 165° C. and a shear rate of 30 s −1 .}

In some embodiments, the resin composition comprises 60 to 90% by weight of the fluoropolymer resin a) and 10 to 40% by weight of the semi-crystalline polyester resin, based on the total weight of the fluoropolymer resin and the semi-crystalline polymer resin b) is included.

In some embodiments, the fluoropolymer resin is selected from polyvinylidene fluoride homopolymers and poly(vinylidene fluoride-hexafluoropropylene) copolymers.

In some embodiments, the fluoropolymer resin has a higher melting temperature than the semi-crystalline polyester resin.

In some embodiments, the resin composition is in the form of flakes or pellets.

In some embodiments, the resin composition is in the form of a powder.

In some embodiments, the resin composition has a particle volume median diameter Dv50 of 10-250 μm, preferably 30-150 μm, as measured by laser granulation.

Another object of the present invention is to provide a method for preparing the above-described resin composition, comprising the steps of:

- In a blender, preferably an extruder, the fluoropolymer resin a) is blended with the semi-crystalline polyester resin b) at a temperature higher than the melting point of the semi-crystalline polyester resin (the semi-crystalline polyester resin is in a molten state) to blend, step to form.

In some embodiments, the method comprises an additional step:

- Converting the blend to flakes, pellets or powder after cooling.

In some embodiments, the fluoropolymer resin does not melt and remains in a solid state during the blending step.

Another object of the present invention is to provide a powder coating composition comprising at least one resin composition as defined above or obtained by the method described above.

In some embodiments, the powder coating composition further comprises a crosslinking agent and optionally other additives selected from pigments, flow agents, degassing agents, waxes, and combinations thereof.

Another object of the present invention is to provide the use of a resin composition as described above in a powder coating composition, preferably a crosslinkable powder coating composition.

In some embodiments, the use is for architectural powder coatings.

Another object of the present invention is to provide a powder coating obtained by applying and optionally curing a powder coating composition as described above.

The present invention can satisfy the above-mentioned needs. In particular, the present invention is easy to pulverize into a powder, and it is possible to derive a coating having one or preferably several of the following advantageous characteristics: good weather resistance, good adhesion, high durability, good solvent resistance, good overall appearance, etc. It provides an economical, stable and homogeneous resin composition. The resin composition of the present invention can be ground using a conventional powder coating manufacturing method and can be used for external coating applications.

This is achieved by using a blend of a fluoropolymer resin and a polyester resin, the polyester resin being a semi-crystalline polyester resin. The use of semi-crystalline polyester resins, and in particular linear aliphatic and/or cycloaliphatic structures, makes it possible to improve the compatibility between fluoropolymer resins and polyester resins. In addition, by adding the polyester resin to the fluoropolymer resin, it is possible to improve the grinding force compared to the fluoropolymer alone.

The present invention will now be described in more detail and without limitation in the following detailed description.

Unless otherwise stated, percentages in this application are percentages by weight.

resin composition

In a first aspect, the present invention relates to a resin composition comprising a blend of:

a) at least one fluoropolymer resin, and

b) at least one semi-crystalline polyester resin.

" Semi-crystalline " means amorphous. The phase change establishing whether a resin is semi-crystalline or amorphous was analyzed by differential scanning calorimetry (DSC), as described in Encyclopedia of Polymer Science and Engineering , Volume 4, pages 482-519, 1986 (Wiley lnterscience). can be detected by A resin is considered amorphous if it does not exhibit identifiable crystallization or melting peaks. A resin is considered semi-crystalline if it exhibits at least one crystallization or melting peak. In general, when different melting peaks are observed in the DSC curve, these multiple peaks are characterized as melting ranges. The term " semi-crystalline " as defined herein includes strictly semi-crystalline polymers ( ie, polymers exhibiting an discernable glass transition temperature Tg) as well as crystalline polymers ( ie, polymers that do not exhibit an discernable glass transition temperature Tg) .

Semi-crystalline (or crystalline) polyester resins, in which they have a heterogeneous morphology ( i.e., they contain a mixture of phases) , are usually opaque and white at room temperature, and, in addition to their relatively low melt viscosity, conventional organic solvents, It differs from conventional amorphous polyester resins used in powder coatings in that it is, for example, much more insoluble than their amorphous counterparts in xylene, white spirit and ketones. Semi-crystalline polyester resins generally have a high degree of structural regularity ( ie , chemical, geometric and/or spatial symmetry).

The resin composition of the present invention comprises, based on the total weight of the fluoropolymer resin and the semi-crystalline polymer resin, the following blends:

a) 10 to 90% by weight of at least one fluoropolymer resin, and

b) 90 to 10% by weight of at least one semi-crystalline polyester resin.

Preferably, the fluoropolymer resin is present in the blend in an amount of from 60 to 90% by weight, more preferably from 70 to 80% by weight, based on the total weight of the fluoropolymer resin and the semi-crystalline polymer resin.

Preferably, the semi-crystalline polyester resin is present in the blend in an amount of from 10 to 40% by weight, more preferably from 20 to 30% by weight, based on the total weight of the fluoropolymer resin and the semi-crystalline polymer resin.

The resin composition according to the present invention may be in the form of flakes or pellets. The flakes or pellets of this resin composition constitute an intermediate product, which is intended to be ground into a powder.

Alternatively, the resin composition may be in the form of a powder (in this case, also referred to as "powder resin composition").

In the powder resin composition of the present invention, the fluoropolymer resin and the semi-crystalline polyester resin form a blend, that is, the powder resin composition of the present invention comprises particles comprising the fluoropolymer and the semi-crystalline polyester resin. As such, it is different from a powder composition resulting from a mixture of a fluoropolymer resin powder and a semi-crystalline polyester resin powder.

Preferably, the particles of the powder resin composition are from 10 to 250 μm, preferably from 30 to 150 μm, for example from 10 to 30 μm, or from 30 to 50 μm, or from 50 to 100 μm, or from 100 to 150 μm, or It has a volume median diameter Dv50 of 150 to 200 μm, or 200 to 250 μm.

Dv50 is a particle size at ^{the 50th} percentile (by volume) in a cumulative particle size distribution. This parameter can be determined by laser granulation.

In some embodiments, the resin composition consists essentially of or consists of at least one fluoropolymer resin and at least one semi-crystalline polyester resin.

Semi-crystalline polyester resin

The semi-crystalline polyester resin is preferably a linear semi-crystalline polyester resin.

Semi-crystalline polyester resins may be based on the polycondensation reaction of (cyclo)aliphatic and/or aromatic polyols with (cyclo)aliphatic and/or aromatic polycarboxylic acids or anhydrides, esters or acid chlorides based on these acids. Examples of suitable polyols are 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, 1,10-decanediol, 1-4 -cyclohexanedimethanol, trimethylolpropane, 2-methylpropane-1,3-diol, hydrogenated bisphenol A (or 2,2-(dicyclohexanol) propane), 2,2,4-trimethyl-1, 3-pentanediol, 2-n-butyl-2-ethyl-1,3-propanediol and 3-hydroxy-2,2-dimethylpropyl 3-hydroxy-2,2-dimethylpropanoate (CA, Reg No.=115-20-4). Suitable poly-carboxylic acids which may be used include linear, (cyclo)aliphatic poly-carboxylic acids and/or aromatic poly-carboxylic acids having 2 to 22 methylene groups, in particular succinic acid, adipic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, terephthalic acid, isophthalic acid, trimesic acid, tetrahydrophthalic acid, hexahydrophthalic acid, 1,4-cyclohexanedicarboxylic acid, trimellitic acid and naphthalene dicarboxylic acid do.

Preferably, however, the semi-crystalline polyester resin has a linear aliphatic and/or cycloaliphatic structure. In particular, the semi-crystalline polyester resin may comprise units derived from:

- at least a poly-carboxylic acid selected from linear aliphatic dicarboxylic acids and/or cycloaliphatic dicarboxylic acids, and

- At least a polyol selected from linear aliphatic diols and/or cycloaliphatic diols.

Preferably, the semi-crystalline polyester resin does not comprise any units derived from aromatic polycarboxylic acids (eg, aromatic dicarboxylic acids) and/or aromatic polyols.

The semi-crystalline polyester resin may consist essentially of or consist of units derived from:

- at least a poly-carboxylic acid selected from linear aliphatic dicarboxylic acids and/or cycloaliphatic dicarboxylic acids, and

- At least a polyol selected from linear aliphatic diols and/or cycloaliphatic diols.

Advantageously, the linear aliphatic dicarboxylic acid is a linear aliphatic C ₄ -C ₈ dicarboxylic acid, more preferably a linear aliphatic C ₄ -C ₆ dicarboxylic acid. For example, it can be a linear aliphatic C ₄ dicarboxylic acid, a linear aliphatic C ₅ dicarboxylic acid, a linear aliphatic C ₆ dicarboxylic acid, a linear aliphatic C ₇ dicarboxylic acid and/or a linear aliphatic C ₈ dicarboxyl acid. It can be acid.

Advantageously, the cycloaliphatic dicarboxylic acid is a C ₆ -C ₈ cycloaliphatic dicarboxylic acid.

Preferably, the poly-carboxylic acid is selected from adipic acid, succinic acid, 1,5-pentanedioic acid, 1,4-cyclohexanedicarboxylic acid and combinations thereof.

Preferably, the linear aliphatic diol is a linear aliphatic C ₂ -C ₈ diol, more preferably a linear aliphatic C ₂ -C ₆ diol, even more preferably a linear aliphatic C ₄ -C ₆ diol. The linear aliphatic diol may be a linear aliphatic C ₂ diol, a linear aliphatic C ₃ diol, a linear aliphatic C ₄ diol, a linear aliphatic C ₅ diol, a linear aliphatic C ₆ diol, a linear aliphatic C ₇ diol and/or a linear aliphatic C ₈ diol .

Advantageously, the cycloaliphatic diol may be a C ₆ -C ₈ cycloaliphatic diol.

In a preferred embodiment, the polyol is selected from 1,6-hexanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol and combinations thereof.

In a particularly preferred embodiment, the semi-crystalline polyester resin is selected from polybutylene succinate, polybutylene 1,4 cyclohexane dicarboxylate and 1,4 cyclohexane dimethanol pentadionate.

For the formation of a polyester resin having significant crystallinity, it is preferred, but not essential, that the poly-carboxylic acid and polyol used in the polycondensation reaction contain an even number of carbon atoms. The use of symmetrically substituted aliphatic cyclic reagents such as 1,4-cyclohexanedicarboxylic acid or 1,4-cyclohexanedimethanol tends to promote crystallinity. However, these reagents may tend to produce semi-crystalline polyester resins with melting temperatures higher than the typical curing temperatures of thermosetting polyester powder coatings; Using this with a diol of the formula HO(CH ₂ ) _n OH or a dicarboxylic acid of the formula HOOC(CH ₂ ) _n COOH, where n is an even number, preferably 2 to 8, for example 4 or 6 It may be desirable to produce a semi-crystalline polyester resin with a lower melting temperature.

This, however, may be the case, for example, by holding the polyester product for a period of time at a temperature intermediate between its glass transition temperature (Tg) and its melting temperature (Tm), or for a period of time before the polyester is cooled to ambient temperature. Certain experimental techniques known to promote crystallinity in polymers that are synthesized (or treated with the final polyester resin) in high boiling organic solvents such as 1,3-dichlorobenzene or diphenylether to remain above the Tm. use or use in polycondensation reactions of monomeric poly-carboxylic acids or polyols containing an even number of carbon atoms is not excluded. These and other techniques for promoting crystallinity in a carboxylic acid group-containing polyester resin may be used alone or in combination.

The semi-crystalline polyester resin may be a mixture of two or more of the above-mentioned resins.

The semi-crystalline polyester resin may have a melting temperature of from 75°C to 150°C, preferably from 90 to 130°C, for example it may be from 75 to 90°C, or from 90 to 100°C, or from 100 to 110°C, or It may have a melting temperature of 110 to 120 °C, or 120 to 130 °C, or 130 °C to 150 °C. The melting temperature can be determined according to ISO 11357-3:1999 Plastics - Differential scanning calorimetry (DSC) Part 3, but with a heating rate of 10° C./min.

The glass transition temperature (Tg) of the semi-crystalline polyester resin is preferably less than 55°C, and may be -20 to 50°C, more preferably -15 to 40°C. In some embodiments. The semi-crystalline polyester resin is -20 to -10 °C, alternatively from -10 to 0 °C, alternatively from 0 to 10 °C, alternatively from 10 to 20 °C, alternatively from 20 to 30 °C, alternatively from 30 to 40 °C, alternatively from 40 to 50 °C; or a glass transition temperature of 50 to 55°C. The glass transition temperature can be measured according to ISO 11357-2 Plastics - Differential scanning calorimetry (DSC) Part 2, but with a heating rate of 10° C./min. The semi-crystalline polyester resin, examined by DSC, may exhibit two glass transitions, one of which is due to the free-moving amorphous region within the polyester resin, and the other whose motion is restricted by adjacent crystals. due to the amorphous region. In these cases, both Tg values are within the above-mentioned temperature range.

The semi-crystalline polyester resin preferably has a hydroxyl number of at least 15 mg KOH/g. This can ensure that it can be properly cured. Most preferably the semi-crystalline polyester resin has a hydroxyl number of at least 20 mg KOH/g. It preferably has a hydroxyl number of 70 mg KOH/g or less, most preferably 40 mg KOH/g or less. In particular, the hydroxyl number is from 15 to 20 mg KOH/g, or from 20 to 25 mg KOH/g, or from 25 to 30 mg KOH/g, or from 30 to 35 mg KOH/g, or from 35 to 40 mg KOH/g, or 40 to 50 mg KOH/g, or 50 to 60 mg KOH/g, or 60 to 70 mg KOH/g. The hydroxyl number can be determined according to DIN 53240-2.

Also preferably, the semi-crystalline polyester resin has an acid number of 10 mg KOH/g or less, more particularly 5 mg KOH/g or less. The acid number can be measured according to ASTM D-1639-90.

A semi-crystalline polyester resin having such a hydroxyl number and an acid number is produced by a polycondensation reaction of a polyol with a poly-carboxylic acid (or anhydride, ester, or acid chloride based on these acids) using an acid in an excess of alcohol. can be

In an alternative and less preferred embodiment, the semi-crystalline polyester resin has an acid number of at least 15 mg KOH/g, most preferably at least 20 mg KOH/g. It may have an acid number of 70 mg KOH/g or less, most preferably 40 mg KOH/g or less. For example, it has a hydroxyl number of 15 to 20 mg KOH/g, or 20 to 30 mg KOH/g, or 30 to 40 mg KOH/g, or 40 to 55 mg KOH/g, or 55 to 70 mg KOH/g It may have an acid value of g. It may have a hydroxyl number of 10 mg KOH/g or less, more particularly 5 mg KOH/g or less. A semi-crystalline polyester resin having such a hydroxyl number and an acid number is prepared by a polycondensation reaction of a polyol with a poly-carboxylic acid (or anhydride, ester, or acid chloride based on these acids) using an alcohol in an excess of acid. can be

A semi-crystalline polyester resin having a hydroxyl number of 15 to 70 mg KOH/g and an acid value of less than 10 mg KOH/g is better with a fluoropolymer resin than a semi-crystalline polyester resin having a high acid number and a low hydroxyl number. will have compatibility.

The number average molecular weight (Mn) of the semi-crystalline polyester resin is preferably at least 1500 or more. With this number average molecular weight, the semi-crystalline polyester resin can contribute to the toughness of the coating. A number average molecular weight Mn of at least 2000 is particularly preferred.

The Mn of the semi-crystalline polyester resin is preferably 15000 or less, and most preferably 5000 or less. Particular mention should be made of number average molecular weights up to 4000. The number average molecular weight Mn can be determined by gel permeation chromatography (GPC).

In some embodiments, the Mn of the semi-crystalline polyester resin is from 1500 to 2000, or from 2000 to 3000, or from 3000 to 4000, or from 4000 to 5000, or from 5000 to 6000, or from 6000 to 7000, or from 7000 to 8000, or from 8000 to 9000, or 9000 to 10000, or 10000 to 11000, or 11000 to 12000, or 12000 to 13000, or 13000 to 14000, or 14000 to 15000.

The semi-crystalline polyester resin may have a heat of fusion of 20 to 100 J/g, preferably 25 to 90 J/g. The heat of fusion can be determined by DSC according to ISO 11357-3:1999, but with a heating rate of 10° C./min. In an example, the heat of fusion is from 20 to 25 J/g, alternatively from 25 to 30 J/g, alternatively from 30 to 40 J/g, alternatively from 40 to 50 J/g, alternatively from 50 to 60 J/g, alternatively from 60 to 70 J/g g, or 70 to 80 J/g, or 80 to 90 J/g.

The semi-crystalline polyester resin may have a melt viscosity of 0.005 to 10 Pa· ^{s at 165° C. and a shear rate of 30 s −1 .} In particular, the melt viscosity is 0.005 to 0.05 Pa.s, or 0.05 to 0.5 Pa.s, or 0.5 to 1 Pa.s, or 1 to 2 Pa.s, or 2 to ^{at 165° C. and a shear rate of 30 s −1 .} 3 Pa.s, or 3 to 4 Pa.s, or 4 to 6 Pa.s, or 6 to 8 Pa.s, or 8 to 10 Pa.s. Melt viscosity can be measured at 165° C. according to ASTM D-4287-00.

Semi-crystalline polyester resins can be prepared as described in DE 10 2006 057837.

Fluoropolymer resin

The fluoropolymer resin has at least one unit selected from a vinyl monomer containing at least one fluorine atom in its main chain, a vinyl monomer containing at least one fluoroalkyl group, and a vinyl monomer containing at least one fluoroalkoxy group. may include. In one example, the monomer is vinyl fluoride; vinylidene fluoride; trifluoroethylene (VF3); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl)ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE) or perfluoro(propyl vinyl) ether (PPVE); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); a product of the formula CF ₂ =CFOCF ₂ CF(CF ₃ )OCF ₂ CF ₂ X, wherein X is SO ₂ F, CO ₂ H, CH ₂ OH, CH ₂ OCN or CH ₂ OPO ₃ H; product of formula CF ₂ =CFOCF ₂ CF ₂ SO ₂ F; a product of the formula F(CF ₂ ) _n CH ₂ OCF=CF ₂ , wherein n is 1, 2, 3, 4 or 5; a product of the formula R ₁ CH ₂ OCF=CF ₂ , wherein R ₁ is hydrogen or F(CF ₂ ) _m and m is 1, 2, 3 or 4; a product of the formula R ₂ OCF=CH _{2 , wherein R 2} is F(CF ₂ ) _p and p is 1, 2, 3 or 4; perfluorobutyl ethylene (PFBE); 3,3,3-trifluoropropene or 2-trifluoromethyl-3,3,3-trifluoro-1-propene.

The fluoropolymer resin may be a homopolymer or a copolymer.

Preferably, the fluoropolymer resin is composed of units from one or more monomers selected from among the aforementioned monomers. Compared to fluoropolymer resins comprising units from non-fluorinated monomers, these fluoropolymer resins can exhibit better weather resistance and thus provide better weather resistance to the resin composition.

Alternatively, the fluoropolymer resin may also include units from non-fluorinated monomers such as ethylene. Advantageously, the fluoropolymer resin is a polyvinylidene fluoride resin.

The polyvinylidene fluoride resin is preferably a homopolymer.

In another embodiment, the polyvinylidene fluoride resin can be a copolymer comprising, or consisting of, vinylidene fluoride units and units from one or more other monomers. Examples of other monomers include vinyl fluoride; trifluoroethylene; chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl)ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE) or perfluoro(propyl vinyl) ether (PPVE); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); a product of the formula CF ₂ =CFOCF ₂ CF(CF ₃ )OCF ₂ CF ₂ X, wherein X is SO ₂ F, CO ₂ H, CH ₂ OH, CH ₂ OCN or CH ₂ OPO ₃ H; product of formula CF ₂ =CFOCF ₂ CF ₂ SO ₂ F; a product of the formula F(CF ₂ ) _n CH ₂ OCF=CF ₂ , wherein n is 1, 2, 3, 4 or 5; a product of the formula R′CH ₂ OCF=CF ₂ , wherein R′ is hydrogen or F(CF ₂ ) _z and z is 1, 2, 3 or 4; a product of the formula R"OCF=CH ₂ , wherein R" is F(CF ₂ ) _z and z is 1, 2, 3 or 4; perfluorobutylethylene (PFBE); 3,3,3-trifluoropropene or 2-trifluoromethyl-3,3,3-trifluoro-1-propene. Hexafluoropropylene is preferred. The polyvinylidene fluoride copolymer may also include units from ethylene monomers. Preferably, when the polyvinylidene fluoride resin is a copolymer, it contains at least 50% by weight, more preferably at least 60% by weight, even more preferably at least 70% by weight, even more preferably at least 80% by weight. contains vinylidene fluoride units.

The fluoropolymer resin may be a mixture of two or more of the above-mentioned resins.

The fluoropolymer may have ^{a shear rate of 100 s −1} and a viscosity measured by capillary flow method according to ASTMD3835 at 230° C. of less than 3000 Pa.s, more preferably less than 1500 Pa.s.

Advantageously, the fluoropolymer resin has a higher melting temperature than the semi-crystalline polyester resin.

powder coating composition

In another aspect, the present invention relates to a powder coating composition comprising the resin composition in a powdered form.

Preferably, the powder coating composition is a curable (or crosslinkable) powder coating composition.

The powder coating composition comprises 5 to 90% by weight, preferably 10 to 90% by weight, more preferably 40 to 90% by weight, still more preferably 60 to 90% by weight, even more preferably based on the total weight of the powder coating composition. preferably 70 to 80% by weight of the fluoropolymer resin.

The powder coating composition comprises from 5 to 90% by weight, preferably from 10 to 90% by weight, more preferably from 10 to 60% by weight, even more preferably from 10 to 40% by weight, more preferably from 5 to 90% by weight, based on the total weight of the powder coating composition. preferably 20 to 30% by weight of a semi-crystalline polyester resin.

In a preferred embodiment, the powder coating composition comprises a crosslinking agent. Preferably, the crosslinking agent is an isocyanate crosslinking agent, more preferably a polyisocyanate crosslinking agent, more preferably a blocked polyisocyanate crosslinking agent. However, other crosslinking agents may be mentioned, such as melamine resins, guanamine resins, sulfonamide resins, urea resins or aniline resins, β-hydroxyalkylamide crosslinking agents, or amine crosslinking agents such as triglycidyl isocyanurate crosslinking agents.

The crosslinking agent may be present in an amount of 2 to 8% by weight, preferably 3 to 6% by weight, based on the total weight of the powder coating composition.

ller, Ulrich Poth, 2nd Revised Edition, Hanover: Vincentz Network, 2011, European Coatings Tech Files, ISBN 978-3-86630-891-6 에 기재된 바와 같은 분말 코팅 제제에 의해 통상적으로 공지되어 있다.The powder coating composition may also include other additives selected, for example, from pigments, flow agents, degassing agents, waxes and combinations thereof. These other additives are preferably in an amount of 10 to 30% by weight, preferably 20 to 25% by weight, based on the total weight of the powder coating composition. These additives are described in "Coatings Formulation" by Bodo M

ller, Ulrich Poth, 2nd Revised Edition, Hanover: Vincentz Network, 2011, European Coatings Tech Files, ISBN 978-3-86630-891-6.

In some embodiments, the powder coating composition consists essentially of, or consists of, the aforementioned ingredients or any combination of the aforementioned ingredients.

Manufacturing method

In another aspect, the present invention is a method for preparing the resin composition, a fluoropolymer resin at a temperature higher than the melting temperature of the semi-crystalline polyester resin to a semi-crystalline polyester resin (the semi-crystalline polyester resin is in a molten state) and blending in a blender, preferably to form a homogeneous blend.

In this method, all of the characteristics described above with respect to the properties of the fluoropolymer resin and the semi-crystalline polyester resin as well as their amounts in the blend with respect to the resin composition apply analogously.

By “ homogeneous blend ” is meant a blend that is macroscopically homogeneous, ie no phase separation is visible to the naked eye.

The blender is preferably an extruder or co-kneader, more preferably a twin-screw extruder or co-kneader.

Preferably, the fluoropolymer resin and the semi-crystalline polyester resin to be blended are in powdered form.

Advantageously, the method further comprises the step of converting the blend into flakes, pellets or powder after cooling of the blend.

When the method comprises converting the blend into a powder, a powder resin composition is prepared, which may be as described above. Preferably, the blend is first formed into a solid compound such as flakes or pellets, which is then ground into a powder. This step can be carried out using any grinding technique, for example a grinder using a hammer mill, pin mill, abrasive disk or impact classifier mill.

The method may comprise selecting powder particles having a desired granulometry, for example by passing the powder through a sieve.

In a preferred embodiment, the fluoropolymer resin does not melt and remains in a solid state during the blending step. In this embodiment, the blending step is performed at a temperature above the melting temperature of the semi-crystalline polyester resin but below the melting temperature of the fluoropolymer resin. The fluoropolymer resin can be used as a powder with a Dv50 of advantageously from 1 to 50 μm, more preferably from 2 to 15 μm. This can improve the grinding ability of the compound formed after the blending step.

The blending step may include blending the fluoropolymer resin and the semi-crystalline polyester resin with the other ingredients as well.

The present invention also relates to a resin composition or a powder resin composition prepared according to the above method.

In another aspect, the present invention relates to a powder coating composition as described above comprising admixing the components of the powder coating composition (i.e., the resin composition described above and for example a crosslinking agent, pigment, flow agent, degassing agent and/or wax). It relates to a manufacturing method.

The mixing step may be a step of dry blending the ingredients in a powdered form.

Alternatively, the mixing step may be a step of melt blending some or all of the ingredients. The blend is then ground into a powder after coagulation. When only some of the ingredients are melt blended and ground into a powder, the resulting particles are dry blended with the remaining ingredients in a powdered form.

The mixing step may be performed in one or several steps, and the components may be mixed in any order.

The present invention also relates to a powder coating composition prepared according to the method.

apply

In another aspect, the present invention relates to the use of said resin composition in powdered form (ie powdered resin composition) in a powder coating composition. The powder coating composition is preferably a crosslinkable powder coating composition.

Preferably, the resin composition or powder coating composition is used for architectural powder coating or automotive paint.

Advantageously, the building powder coating has high weather resistance. For example, the coating may exhibit a gloss retention of at least 80% after 500 hours according to ASTM D-523-60E.

Architectural powder coatings can last more than 10 years.

In another aspect, the present invention relates to a method for coating a substrate comprising:

- applying the resin composition (ie, powder resin composition) or the powder coating composition in a powdered form on a substrate;

- Melting the powder resin composition or powder coating composition.

The substrate may be wood or metal such as aluminum and steel grades.

Melting of the powder resin composition or powder coating composition can be carried out by heating the powder-coated substrate at a temperature higher than the melting temperature of the powder, for example, at a temperature of 160° C. to 280° C., preferably 180° C. to 250° C. .

Preferably, the substrate coating process comprises curing the powder resin composition or powder coating composition applied on the substrate. This step may be performed simultaneously with the step of melting the powder resin composition or the powder coating composition. Curing can be induced by heating the powder resin composition or powder coating composition at a temperature of, for example, 160°C to 280°C, preferably 180°C to 250°C.

The coating of the substrate can be carried out by electrostatic spraying. In this case, the method for coating the substrate may comprise the following steps:

- charging the powder (powder resin composition or powder coating composition);

- spraying the charged powder onto the substrate;

- heating the substrate coated with the powder at a temperature higher than the melting temperature of the powder.

In another aspect, the present invention relates to a powder coating resulting from the use of at least one resin composition described above.

The present invention relates to a powder coating obtained by applying and optionally curing at least one powder coating composition described above.

The invention also relates to an object comprising said powder coating.

Example

The following examples illustrate the invention without limiting it.

Example 1

Compounds A to D were prepared as follows:

- Compound A:

PVDF homopolymer with a melting point of 169°C and a melt viscosity of 6 kPo,

· OH functional semi-crystalline polyester (polybutyl) having an OH functionalization degree (or hydroxyl number) of 30 to 45 mg KOH/g, a melting point of 110° C., a heat of fusion of 20.9 J/g and a melt viscosity of less than 1 Pa.s lensuccinate),

· a crosslinking agent (Vestagon B-1530, Evonik), and

· TiO ₂ pigment (CR95, Ishihara)

was blended at a weight ratio of 52.5/19.6/2.9/25 and 140°C;

- Compound B:

· PVDF homopolymer having a melting point of 169°C and a melt viscosity of 6 kPo,

· OH functional semi-crystalline polyester (polybutylene succinate) having an OH functionality of 30 to 45 mg KOH/g, a melting point of 110° C., a heat of fusion of 20.9 J/g and a melt viscosity of less than 1 Pa.s,

· crosslinking agent (Vestagon B-1530, Evonik),

· benzoin, and

· TiO ₂ pigment (CR95, Ishihara)

was blended at a weight ratio of 53.2/19.7/3.1/1/23 and 110°C.

- Compound C:

PVDF homopolymer with a melting point of 169°C and a melt viscosity of 6 kPo,

PVDF-HFP copolymer containing 17 wt.% HFP, melting point 115° C. and viscosity 3 kPo,

· OH functional semi-crystalline polyester (polybutyl) having an OH functionalization degree of 30 to 45 mg KOH/g, a melting point of 110° C., a heat of fusion of 20.9 J/g and a melt viscosity of less than 1 Pa.s as determined by ISO 3129 lensuccinate),

· crosslinking agent (Vestagon B-1530, Evonik),

· benzoin, and

TiO ₂ Pigment (R960, Dow)

was blended at a weight ratio of 49.2/4/19.7/3.1/1/23 and 110°C.

- Compound D:

· Amorphous polyester (Reafree 5700, Arkema) having an acid functionalization degree (or acid number) of 30 to 36 mg KOH/g, a glass transition temperature of 61°C, and a melt viscosity of 15 Pa.s as measured by ASTM D4287 at 165°C Coating Resins),

· crosslinking agent (TGIC),

· benzoin, and

· TiO ₂ pigment (CR95, Ishihara)

was blended at a weight ratio of 70.7/5.3/1/23 and 110°C.

- Compound E:

PVDF homopolymer with a melting point of 169°C and a melt viscosity of 6 kPo,

· OH functional amorphous polyester (Reafree 17014, Arkema Coating Resins) having an OH functionalization degree of 38 to 48 mg KOH/g, a glass transition temperature of 60° C., and a melt viscosity of 30 Pa.s as measured by DIN 53229,

· crosslinking agent (Vestagon B-1530, Evonik),

· benzoin, and

TiO ₂ Pigment (R960, Dow)

was blended at a weight ratio of 51.8/18.4/3.8/1/23 and 110°C.

- Compound F:

PVDF homopolymer with a melting point of 169°C and a melt viscosity of 6 kPo,

· an amorphous polyester (Reafree 5700, Arkema Coating Resins) having an acid functionalization degree of 30 to 36 mg KOH/g, a glass transition temperature of 61°C, and a melt viscosity of 15 Pa.s as measured by ASTM D4287 at 165°C;

· crosslinking agent (TGIC),

· benzoin, and

TiO ₂ Pigment (R960, Dow)

was blended at a weight ratio of 51.8/20.7/1.6/1/23 and 110°C.

- Compound G:

PVDF homopolymer with a melting point of 169°C and a melt viscosity of 6 kPo,

PVDF-HFP copolymer containing 17 wt.% HFP, melting point 115° C. and viscosity 3 kPo,

· OH functional semi-crystalline polyester (polybutylene succinate) having an OH functionality of 30 to 45 mg KOH/g, a melting point of 110° C., a heat of fusion of 20.9 J/g and a melt viscosity of less than 1 Pa.s,

· crosslinking agent (Vestagon B-1530, Evonik),

· degassing agent (BYK3955P, BYK), and

TiO ₂ Pigment (R960, Dow)

was blended at a weight ratio of 46.3/5.8/20.3/2.9/2/22.8 and 110°C.

All compounds were individually ground in a high-speed blender and sieved to a 125 μm mesh. The sieved powder was electrostatically sprayed onto a chromed aluminum panel and baked at 220° C. for 15 minutes.

The coatings from compounds A to C and G are according to the invention, the coatings from compounds D to F are comparative examples.

The coating was then evaluated for the following properties:

- Cross hatch bonding, according to AAMA 2605-13 8.4.1.1;

- Cross hatch adhesion with reverse impact, according to ASTM D3359-02;

- Direct and reverse impact, according to AAMA 2605-13 A5.2.2;

- MEK solvent resistance according to ASTM D4752 (200 double friction); This test makes it possible to evaluate resistance to solvents and cleaning chemicals;

- grinding capacity, according to the following method: grinding 20 g of material in a high-speed blender such as Ultra Centrifugal Mill ZM 200 by Retsch for 15 seconds; Weigh the material that has passed through the 125 μm open sieve.

- According to ASTM D3451, the weather resistance property was evaluated by gloss retention after 500 hours of QUV test. If the gloss retention is greater than 80%, the coating is marked as “pass” , and if the gloss retention is less than 80%, the coating is marked as “failed”.

The results are presented in the table below:

Claims (15)

A resin composition comprising, based on a total weight of a fluoropolymer resin and a semi-crystalline polymer resin, a blend of:
a) from 10 to 90% by weight of at least one fluoropolymer resin and
b) from 90 to 10% by weight of at least one semi-crystalline polyester resin;
The semi-crystalline polyester resin preferably has a linear aliphatic or/and cycloaliphatic structure. The resin composition according to claim 1, wherein the semi-crystalline polyester comprises, preferably consists of, units derived from:
- at least poly-carboxylic acids selected from linear aliphatic dicarboxylic acids and/or cycloaliphatic dicarboxylic acids, and
- at least a polyol selected from linear aliphatic diols and/or cycloaliphatic diols;
The poly-carboxylic acid is preferably selected from linear aliphatic C ₄ -C ₈ dicarboxylic acids, preferably linear aliphatic C ₄ -C ₆ dicarboxylic acids, and/or cycloaliphatic dicarboxylic acids, more preferably preferably selected from adipic acid, succinic acid, 1,5-pentanedioic acid, 1,4-cyclohexanedicarboxylic acid, and combinations thereof; The polyol is preferably selected from linear aliphatic C ₂ -C ₈ diols, preferably linear aliphatic C ₂ -C ₆ diols, more preferably linear aliphatic C ₄ -C ₆ diols, and/or cycloaliphatic diols, more Preferably, the resin composition is selected from 1,6-hexanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, and combinations thereof. The resin composition according to claim 1 or 2, wherein the melting temperature of the semi-crystalline polyester resin is from 75°C to 150°C, preferably from 90 to 130°C. 4 . The semi-crystalline polyester resin according to claim 1 , wherein the glass transition temperature of the semi-crystalline polyester resin is less than 55° C., preferably -20 to 50° C. as measured by DSC at a heating rate of 10° C./min; more preferably -15 to 40° C., and/or the semi-crystalline polyester resin has a heat of fusion of 20 to 100 J/g, preferably 25 to 90 J/g as measured by DSC at a heating rate of 10° C./min. A resin composition having 5. The semi-crystalline polyester resin according to any one of claims 1 to 4, wherein the semi-crystalline polyester resin has a hydroxyl number of 15 to 70 mg KOH/g, preferably 20 to 40 mg KOH/g and less than 10 mg KOH/g; Preferably, the resin composition has an acid value of less than 5 mg KOH/g. 6. The semi-crystalline polyester according to any one of claims 1 to 5, wherein the number-average molecular weight Mn of the semi-crystalline polyester is from 1500 to 15000, preferably from 2000 to 5000 and/or the semi-crystalline polyester resin is at 165° C. and 30 s ^- A resin composition having a melt viscosity of 0.005 to 10 Pa.s at a shear rate of ^1. 7. A composition according to any one of claims 1 to 6, wherein, based on the total weight of the fluoropolymer resin and the semi-crystalline polymer resin, 60 to 90% by weight of said fluoropolymer resin a) and 10 to 40% by weight of said fluoropolymer resin a). A resin composition comprising the semi-crystalline polyester resin b). 8. The resin composition according to any one of claims 1 to 7, wherein the fluoropolymer resin is selected from polyvinylidene fluoride homopolymers and poly(vinylidene fluoride-hexafluoropropylene) copolymers. 9. The resin composition according to any one of claims 1 to 8, wherein the fluoropolymer resin has a higher melting temperature than the semi-crystalline polyester resin. 10. The method according to any one of claims 1 to 9, in the form of flakes or pellets; or in the form of a powder, preferably having a particle volume median diameter Dv50 of 10-250 µm, preferably 30-150 µm, as measured by a laser granulation method. Steps to follow:
- in a blender, preferably an extruder, by blending the fluoropolymer resin a) with the semi-crystalline polyester resin b) at a temperature higher than the melting point of the semi-crystalline polyester resin (the semi-crystalline polyester resin is in a molten state), forming a blend;
- optionally converting the blend into flakes, pellets or powder after cooling
A method for producing the resin composition according to any one of claims 1 to 10, comprising a. The method of claim 11 , wherein the fluoropolymer resin remains in a solid state without melting during the blending step. at least one resin composition as defined according to claim 10 or obtained by the method of claim 11 or 12, preferably a crosslinking agent, and optionally pigments, flow agents, degassing agents, waxes and combinations thereof Powder coating composition further comprising another additive selected from. Use of the resin composition of any one of claims 1 to 10 in a powder coating composition, preferably in a crosslinkable powder coating composition, preferably for architectural powder coating. A powder coating obtained by applying and optionally curing the powder coating composition of claim 13 .